The field of the invention is lighting and the invention relates more particularly to lighting of the type used for professional photographers, for set lighting for motion pictures, stage, television and the like.
One of the earliest problems encountered in motion picture photography was the need for sufficient light for exposure. Whereas in still photography the exposure could be extended to provide enough light to expose the film, for motion picture work, this exposure was by necessity limited and, thus, most early films had to be taken out of doors in direct sunlight or under a skylight. Artificial lighting was developed and soon the very bright light emitted by an electric arc was used and referred to as a "klieg" light. For most motion picture and television work, a general level of illumination is established throughout the set to approximate daylight conditions. Second, concentrated beams of light are directed onto people or areas that need to be clearly set forth in the picture. With the introduction of color, not only is the intensity of light important, but also the color of the light. Incandescent lights tend to be far more yellow than electric arc light. The color of the light is typically quantified by a temperature expressed in degrees Kelvin. For instance, a common source light, using a 2,000 watt halogen cycle/quartz bulb provides a light of 3,200 degrees Kelvin. Such lamps can be filtered with a jel filter which increases the color from 3,200 degrees Kelvin to 5,600 degrees which is equivalent to outdoor sunlight.
The problem with the use of lamps having a 2,000 watt halogen cycle/quartz bulb is that such lamps generate a great deal of heat which is, of course, proportionate to the 2,000 watts of energy being used. Such lamps often weigh as much as eighty pounds and are large, bulky and fragile. Not only do such lamps generate a large amount of heat surrounding the bulb, but they also radiate a large amount of heat which, in view of the fact that many such lamps are used together to light the action, can become very uncomfortable for the actors. Another substantial problem with the use of the commonly used 2,000 watt lamps is the difficulty in transporting such lamps to a remote sight. As mentioned above, such lamps typically weigh up to eighty pounds and are large and fragile. Because of their substantial weight, the stands which hold them also must be very sturdy, and as a result, are also heavy and bulky.
Yet another disadvantage of the widely used 2,000 watt, 120 volt, 3,200 degree Kelvin quartz globe is that they are relatively inefficient in their use of light. For instance, although the bulb, itself, contains a small reflector, a large amount of the light emitted by the Tungsten filament is not reflected out of the lamp but instead impinges upon the inner surface of the lamp further increasing the heat and decreasing the amount of light projected from the lamp. Another disadvantage of such heat is the difficulty of changing the bulb when one of the bulbs burns out. The heated assembly is too hot to handle and must cool at least in part before a bulb change. Although such bulbs are rated at one hundred fifty hours, when they have to be moved frequently, the life decreases to about fifty hours. Yet another disadvantage is the amperage required by a 2,000 watt bulb. Typically sixteen amps are required which is above that permitted by most household circuit breakers which are limited to fifteen amps. Therefore, special generators are typically used to provide sufficient amperage in remote locations. Still further, a Fresnel lens must typically be used to focus the light beam from such lamps and still further, light is lost.
A common home movie or video recorder light comprises a halogen cycle bulb in a single reflector typically attached to the movie camera or VCR camera. Lamps attached to cameras are typically not very useful for professional use because they create a light pattern which may be readily seen in the finished picture. They further create a very sharp shadow which would be unacceptable for most professional purposes. Such lamps are, however, used for remote locations and the decreased quality of light can also be seen during the filming of interviews at fires, floods and the like at night. While such lighting is adequate for emergency use such as this, it is unacceptable for professional television, motion pictures, stage or for professional photographers.
It is, thus, apparent that the presently used system has many shortcomings.